At an art gallery, you can simply skip the works that don't interest you. Abandoning a novel is often a gradual process rather than a decisive action: it sits by the bed unopened for a day or two, another novel is started with the idea of returning to the first book, then the unloved book gathers dust.

It can, in fact, be quite an aggressive thing to do – a two-legged version of two fingers held aloft, if it's done while the actors are on stage. But while for some the lure of the merlot is so great that leaving is easy, deciding not to return after the interval (if there is one) is often a tricky decision, involving negotiation with those you are with, as well as complicated calculations of time and of emotional and financial outlay. The more money invested or more significant the occasion, the harder it is to leave even if you are having a grim time, although sleep is a strategy that many theatre-goers regularly employ.

And once you've left the venue, there is no going back. You may never know that Nora leaves, or that those shipwrecked twins in Twelfth Night are reunited. There's probably nothing worse than being informed afterwards that the second half of a production you spurned was a complete belter in which everything suddenly came together to make brilliant sense.

So, have you left shows before the curtain call – and have you ever kicked yourself afterwards for it?